1. Field of the Invention
The present invention relates to a fixing device with a locking mechanism, and particularly to a fixing device with a disengagable locking mechanism capable of securely preventing a hexagon-head bolt or screw from loosening or coming off.
2. Description of the Related Art
Various types of locking mechanisms have been proposed and improved for a bolt with a hexagonal head wherein the bottom face of the hexagonal head of the bolt is frictionally engaged with a washer to prevent the bolt from loosening.
Examples of such locking mechanisms are as follows. Japanese Utility Model Publication (kokoku) No. 53-32199 discloses a locking mechanism in which a capsule containing an adhesive is placed inside a washer, and the capsule is broken as a bolt is fastened, so that a member to be fastened and the head of the bolt are bonded together by the adhesive flowing out of the capsule. Japanese Patent Publication (kokoku) No. 50-29102 discloses a locking mechanism in which a thick elastic ring is attached to a washer, and the elastic ring is crushingly pressed by the head of a bolt as the bolt is fastened, thereby increasing the rotational friction of the bolt. Japanese Patent Publication (kokoku) No. 43-25405 discloses a locking mechanism in which a rimmed locking washer is used to resist a reverse rotation of a bolt head. Japanese Utility Model Publication (kokoku) No. 4-7907 discloses a locking mechanism in which a projection formed on a washer is caused to engage with an annular groove formed in the bottom face of the head of a bolt, thereby preventing the bolt from loosening. These locking mechanisms, however, have problems that their actions for locking bolts are insecure, that repeated use is almost impossible, and that the bolts or nuts with which they are used require additional machining.